Thin sheet metal workpieces which can range in thickness from the thickness of a foil (submillimeter thickness) to a thickness of several millimeters, have been welded heretofore by superimposing the edge strip of one of the sheet metal workpieces on an edge strip of another or by butting the edges of the workpieces together utilizing as a heating means a laser beam (see, for example German patent No. 733 200, German open application No. 36 00 532, "Laser in Elektrotechnologie und Materialbearbeitung", 1982, Akad. Verl. -Gesellschaft Geest und Portig KG, Pages 128, 148 to 155).
In the first case, there is a local doubling of the thickness of the sheet metal welded together which is undesirable to say the least and frequently is intolerable.
In the butt welding of such edges (see German open application No. 37 13 527) the edge regions which are to be joined require machining and treatment in an expensive and time-consuming manner to allow a reliable, dense, tight and secure weld seam to be obtained.